The long-term goal of this project is to predict outcomes of laryngeal phonosurgery with physiologically based voice simulation. The proposed research will move towards this goal by developing a model of vocal fold posturing. Vocal fold posturing, a fundamental aspect of phonation control, is defined as adduction, abduction, or elongation of the vocal folds. Because posturing is based on laryngeal joint mechanics and soft tissue deformation, fundamental theories of continuum mechanics are used to formulate this model. The application of continuum mechanics to laryngeal posturing requires an accurate geometric and mechanical description of various tissues in the larynx, such as the vocal ligament and intrinsic laryngeal muscles. Furthermore, because many of these tissues are fibrous and thus have distinct lines of action, a portrayal of passive and contractile stress contributions and fiber direction is needed. The specific aims of the current project are: I. To mathematically represent the orientation of differentiated laryngeal muscle bundles, allowing for distributed muscle forces over various cartilages. II. To create, with the distribution of intrinsic muscle bundles, a three-dimensional finite element model of vocal fold mechanics that can predict both the speed and the range of vocal fold medialization and lateralization. III. To simulate a Type I thyroplasty phonosurgery and predict the resultant glottal configuration as well as the resultant stress distribution in the repaired vocal fold. It is expected that the posturing model will have a significant impact on surgically based voice therapies, as well as on vocal fold modeling in general and post-surgical therapy.